Supplemental iron can be given in several ways. One of the most common supplements for iron deficient anaemia is 325 mg of ferrous sulphate taken twice daily. If the anaemia does not improve try taking Vitamin C with the iron supplement. This can improve the absorption of the iron in the gastrointestinal tract. There are some prescription supplements that combine both iron and Vitamin C.
Iron is known to be associated with constipation, so a stool softener may be necessary. But try prune juice first, as it is high in fibre and is also a good source of iron. Also, iron may irritate the stomach and exacerbate the nausea and vomiting in early pregnancy.
Iron supplements should only be taken under your doctor's supervision. There are some types of anaemia that cannot be treated with iron supplements. Taking iron in these cases may do more harm than good.